This invention relates to a carton blank and carton for packaging and dispensing a printing blanket, and more particularly to a method of using a carton which permits the alignment and controlled feeding of a metal-backed printing blanket onto a rotating print cylinder of a printing press.
The most common commercial printing process is offset lithography. In this printing process, ink is offset from a printing plate to a rubber blanket mounted on a cylinder before being transferred to a substrate, such as paper. Typically, the cylinder comprises a metal cylinder having an encircling rubber printing blanket which is releasably mounted to the cylinder. The rubber printing blanket may be reinforced with either a cloth back or a metal back. Unlike the cloth back, the metal back adds durability to the carried rubber layer(s) on the blanket by removing stress which occurs from tensioning the printing blanket as it is mounted on the metal cylinder.
However, with a cloth back the printing blanket may be rolled upon removal from its shipping carton and maintained as a roll by finger pressure. This minimal amount of handling pressure permits two operators to easily align the blanket in a locking device which is typically located in a longitudinal gap in the metal cylinder. Additionally, as the cylinder rotates to mount the blanket thereon, the operators can easily control the tension and alignment of the unrolling blanket with such minimal handling pressure.
With a metal-backed printing blanket, the metal sheet strongly desires to uncoil upon removal from a conventional shipping carton. The handling pressure needed to maintain the metal-backed blanket as a coil makes it difficult for the operators to properly insert and align the blanket into the locking device of the cylinder. Additionally, the resistance of the blanket to being coiled makes it difficult to control the tension and alignment of the blanket as it unrolls onto the rotating cylinder. Such problems have resulted in a high percentage of ruined metal-backed blankets due to improper installation.
Accordingly, there is a need in the printing industry for an improved procedure or device which maintains the coiled condition of the blanket and permits the dispensing of a metal-backed printing blanket to a print cylinder in a controlled fashion.
The above-mentioned needs are met by the present invention in which a shipping carton for a metal-backed printing blanket is provided. The shipping carton is adapted to permit the proper loading of the blanket onto a printing press cylinder. As it will appear in the more detailed description and drawings, the carton provides for the formation of a lengthwise slit from which to dispense the enclosed blanket in a controlled fashion. The shape of the carton may vary, and encompasses any common geometrical shape including rectangular, triangular, cylindrical, and the like.
In a first embodiment, the carton is substantially rectangular in shape, is formed preferably from a one piece blank of retail packaging type cardboard, and has from one end of the blank to the other first, second, third, fourth, and fifth panels. The first and fifth panels are folded from the second and fourth panels, respectively, so that the first panel lies substantially parallel to and outside the fifth panel with its edge secured adjacently to the fourth panel. Pull tabs are provided in the third panel in order to permit the formation of a lengthwise slit adjacent the edge of the third panel by an operator. The slit once formed, permits the mounting end of the metal-backed printing blanket to be removed from the carton. Reference lines are also optionally provided on the third panel. These reference lines may be used to draw alignment marks on a dispensed portion of the printing blanket for proper insertion into a locking device of the blanket cylinder.
All but the third panel have pairs of flaps together forming the two sides of the carton. In particular, the fourth panel includes a pair of doubled-winged flaps having handholds. Each double-winged flap comprises a body foldably attached between inner and outer flaps. The body forms a space between the inner and outer flaps when the outer flap is folded over the inner flap. All the flaps of the carton together help to form strong handholds in the sides of the carton. The handholds permit two operators to have control of the blanket for tension and proper alignment as the blanket is fed out of the carton and mounted on a rotating cylinder.
In second and third embodiments of the present invention, the carton is provided in the form of a cylindrical tube and a triangular tube, respectively. In these embodiments, the mounting end of the rolled blanket is still dispensed through a side wall of the carton. Handles and/or indentations are also provided such that the carton may be easily gripped to facilitate control over the alignment and tension of a dispensing blanket from the carton onto a rotating blanket cylinder. Alignment marks may additionally be provided to each of these embodiments.
In accordance with one aspect of the present invention, provided is a carton blank for a carton to contain a metal-backed printing blanket in a roll and from which to dispense the blanket. The blank comprises at least first, second, and third panels in the order named from one end of the blank to the other and foldable with respect to each other, one of the panels being capable of dispensing the blanket in a controlled fashion, and at least one of the panels having a pair of side flaps to form sides of the carton.
In accordance with another aspect of the present invention, provided is a carton to contain a metal-backed printing blanket in a roll, the carton comprising at least one panel through which to dispense the printing blanket.
In accordance with yet another aspect of the present invention, provided is a carton to contain a metal-backed printing blanket in a roll and from which to dispense the printing blanket. The carton comprises first, second, third, fourth, fifth, and side panels in which a lower edge of the first panel is secured to the fifth panel. Pull tabs for forming a lengthwise slit in the carton are provided generally in the plane of the third panel.
In accordance with still another aspect of the present invention, provided is a method of mounting a rolled printing blanket to a blanket cylinder in a printing press. The method comprises the steps of providing a carton containing the rolled printing blanket, opening a slit lengthwise in the carton to withdraw a mounting end of the printing blanket, and securing the mounting end in a locking device of the cylinder. The method further includes rotating the cylinder, and controlling the alignment and tension of the printing blanket as it mounts on the rotating cylinder until the printing blanket is completely dispensed from the carton.
These, and other features and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.